The invention relates generally to pulse detonation assemblies, and more particularly, to hybrid pulse detonation-turbine engines.
Pulse detonation engines are a promising propulsion technology, in view of the lower entropy rise of detonative processes, as compared to constant pressure deflagration. Consequently, pulse detonation engines have the potential to propel vehicles at higher thermodynamic efficiencies than are achieved with deflagration-based engines.
Recently, hybrid pulse detonation-turbine engines have been proposed, where the steady flow constant pressure combustor is replaced with a number of pulse detonation chambers. See, for example, U.S. Pat. No. 6,666,018, Butler et al., entitled “Combined cycle pulse detonation turbine engine” and U.S. Pat. No. 6,442,930, Butler et al., entitled “Combined cycle pulse detonation turbine engine.” Although specific concepts vary in their implementation, a common feature incorporates the idea of the exhaust from the multiple pulse detonation chambers driving a downstream turbine.
One challenge in optimizing multi-tube pulse detonation assemblies is designing the downstream geometry. The downstream geometry affects performance in several ways. For example, in multi-tube pulse detonation assemblies, the downstream shock interactions of one tube (chamber) may adversely affect the operability of neighboring chambers. In particular, the shock may propagate up an adjacent chamber, thereby disturbing the fill cycle of that chamber. This undesirable interaction is particularly relevant for hybrid pulse detonation-turbine applications, where there may be a strong shock reflection from the turbine face.
Another challenge for hybrid pulse detonation-turbine assemblies is reducing flow losses prior to work extraction by a downstream turbine. Consequently, controlling the geometry of the transition region from the pulse detonation chamber to the turbine inlet is critical to reducing flow losses.
Accordingly, it would be desirable to provide a pulse detonation assembly and hybrid pulse detonation-turbine engine that reduce undesirable interactions between neighboring pulse detonation chambers. It would further be desirable to reduce the expansion losses of the high pressure gases discharging from the pulse detonation chamber.